Background: Rituximab in the combination of CHOP chemotherapy has been widely used as the standard treatment for several kinds of B-cell non-Hodgkin lymphoma (B-NHL). Inactivation of phosphorylation of STAT3 plays an essential role in rituximab-induced anti-proliferative activity in B-cell lymphoma. However, the relationship between STAT3 genetic polymorphisms and clinical response to standard frontline treatment with rituximab has not been well illustrated yet. Methods: In this study we analyzed the STAT3 polymorphisms and prognosis of 166 diffuse large B-cell lymphoma (DLBCL) patients who were treated with rituximab from 2007 to 2010. Determination of the STAT3 polymorphisms of rs2293152 from genomic DNA was achieved by Sanger chain termination sequencing. Results: We did not observe obvious correlation between patients’ disease features and STAT3 polymorphisms, but patients with homozygous genotypes at rs2293162 showed a trend of higher CR rate than those with the heterozygous genotype, especially in non-GCB subgroup (p = 0.011). Furthermore, homozygous genotypes GG and CC also showed advantages of long-term survival compared with heterozygous genotype patients (p = 0.022). Conclusions: These results suggest that STAT3 polymorphisms could be a suitable biomarker related to clinical outcome of DLBCL patients treated with rituximab.